Testing formation fluids in downhole conditions can be a challenging endeavor that presents many problems for engineers, drillers and scientists. To aid in the testing of such formation fluids, different apparatus may be used to accomplish the testing, including probes and single packer apparatus. Single packer apparatus have many advantages compared to standard testing devices. Single packer apparatus may be used to separate different segments of the wellbore so testing may be performed at a variety of pressures, for example.
In order to separate the different segments of a wellbore, the single packer device is positioned downhole at a desired elevation. The single packer, during placement, is generally in a minimum diameter configuration to allow the single packer to be fit and moved within the wellbore. Once the single packer is at the desired elevation, the single packer is expanded such that the outer diameter of the single packer contacts the inner diameter of the wellbore. The expansion may occur, for example, through actuation of an internal mandrel.
Expansion of the single packer can lead to significant problems, due to many issues. Environmental issues can cause stresses on different sections of the single packer system and thus, it would be desirable to eliminate such stresses.
The increase in diameter of the single packer system can cause the outer covering of the single packer to undergo significant stresses. A potential failure of the outer covering can compromise not only sampling efficiency, but also safety of the single packer as the outer covering is used as a bearing surface.
Currently, there is no protection from potential failure of the outer covering of a single packer, especially at the anterior ends of the single packer. Such ends are prone to over expansion as the single packer system ends have stress concentrations at the ends of the configurations.